Escapement



- Feb. '15,"19383 4F. EIBERT 2,108,112

ESCAPEMENT Filed Nov. 20, 1934 2 Sheets-Sheet l Feb. 15,-1938.- l

F EIBERT 2,108,112 ESCAPEMENT Filed Nov. 2o, 1934 l2 sheetssheet 2 sametime eliminates Patented Feb. 15,

ESCAPEMENT Fritz Eibert, Munich, G

rer

Fries ermany, assigner to Robert Wolff, Basel, Switzerland ApplicationNovember 20, 1934, Serial No. 753,796

In Germany April 3, 1934.

5 Claims.

The present invention relates to an improved escapement and moreparticularly to a paper carriage escapement for typewriters.

In order to speed up the step by step displace- J ment o1" the papercarriage in the same time to utilize the typewriters and at forceexercised by the carriage spring on the escapement for speeding up thereturn movement of the depressed key lever, it has been already proposedto provide the displacement pawl with a wedge like surface engaged byrack under the teeth of the ratchet wheel or the influence of thecarriage spring.

As a modification of the same principle it has been also suggested toprovide the ratchet wheel with teeth having an oblique or wedge likesurface which were engaged by a displacement pawl of conventionaldesign.

Although these arrangements have been successful in speeding uptheoperation of the paper carriage and of the key levers all escapements ofthis type had the common disadvantage that frequently the paper carriagewould be displace operator was too slow ger from the depressed d byseveral steps if the in withdrawing his finkey. Of course, thiscircumstance interfered seriously with the correct operation of thetypewriter confronting' the art with a problem for which as far as I amaware of no satisfactory solution has been offered.

I have discovered that it is possible to eliminate all of priorescapements and the aforesaid shortcomings of the to provide acompletely satisfactory and reliable escapement device in a remarkablysimple manner.

It is an object of the vide an improved paper present invention toprocarriage escapement for typewriters which permits quick and easydisplacement of the paper carriage and utilizes part of the energystored in the carriage spring for the return movement of the key lever,type lever, and the like.

It is another object of the present invention to provide an escapeme ntdevice for typewriters which embodies the advantages of wedge-likesurfaces in its co-operating parts and at the the danger of unintendedmovements of the paper carriage when the depressed key lever is releasedtoo slowly.

A further object of the invention is to incorporate a safety catch intoone of the co-operating members of the escapement and thereby insureeasy and reliable displacement of the paper carriage at all operation.

speeds or conditions oi The invention also contemplates an improvedratchet which is provi ded with wedge shaped teeth having a safety catchwhich can be easily manufactured and which can be used for convertingescapements of conventional design into my improved escapement.

Other objects and advantages of my invention will become apparent fromthe following description taken in conjunction with the accompanyingdrawings, in which:-

Fig. 1 shows an embodiment of my invention including a vertical sectionof the key action and illustrated the displacement pawl in its normal orrest position;

Fig. 2 is a fragmentary View of the pawls and ratchet shown in Fig. 1illustrating the displacement pawl in its position when the type leveris depressed;

Fig. 3 is a similar view depicting the displacement pawl partly returnedby the ratchet tooth under the innuence of the carriage spring said pawlbeing locked by the safety catch due to the 20 key not being releasedyet;

Fig. 4 shows the displacement pawl in the last part of its returnmovement;

Fig. 5 is a fragmentary View of a modified embodiment or" the inventiondepicting the position of the displacement pawl when the type lever isdepressed;

Fig. 6 is a similar view illustrating the displacement pawl when thetype lever has been partly returned but the key is not released yet;

Fig. 7 shows the displacement pawl in its position of rest;

Fig. 8 shows another modied embodiment of the invention; Y

Fig. 9 is a fragmentary View of the pawls and ratchet shown in Fig. 8depicting the displacement pawl in its position of rest;

' Fig. 10 is a similar View illustrating the pawls when one oi the keylevers is depressed;

Fig. li shows the displacement pawl partly returned and engaged by thesafety catch on the ratchet wheel tooth;

Fig. l2 is a somewhat fragmentary plan view oi my improved ratchet wheelwith safety catch;

Fig. 13 shows the assembly of my improved ratchet wheel;

Fig. i4 is a iront elevational view, somewhat fragmentary, of myimproved ratchet wheel having a safety catch in co-operation with a con-Ventional displacement pawl; and

Figs. l5 and 16 show diagrammatically two consecutive steps in theoperation of the escapement illustrated in Fig. ifi.

According to the principles of the present invention, a novelcombination is provided involving a ratchet and an escapement pawleither of which is provided with a wedge-like surface and a safetycatch. The safety catch preferably has a short angular surface which ispreferably normal or perpendicular to the direction in which the teethof the ratchet wheel are moving. This angular surface will act as asafety catch and will detain the ratchet wheel teeth momentarily duringits sliding off movement, if the depressed key is not released fastenough. In some cases, I prefer to provide the displacement pawl or thepawl carrier with a very light spring in order to return the pawl orcarrier to its normal position of rest.

The principle of my invention can be also employed in escapements of thetype where the wedge-like surface is on the teeth of the ratchet wheel.In this case I add the angle surface or safety catch to the teeth of theratchet wheel, which I provide with a short extension surface preferablyat right angles or normal to the direction of movement of the ratchetwheel. The practical results will be the same as when the safety catchis applied to the displacement pawl. I found that the lattermodification is especially adaptable to be used as an attachment orreplacement part for typewriters of conventional design, because theconventional ratchet wheel can be easily exchanged and replaced with myimproved ratchet wheel provided with wedge-like teeth and safety catchthereby improving the performance of the typewriter quite considerably.Of course, an old pawl in a conventional typewriter can be replaced justas easily with a new pawl having a wedge-like surface and a safety catchas the replacement of the old ratchet wheel.

Referring more particularly to Figs. 1 to 4, ratchet wheel 7c isrotatably arranged between two bearings Z and m and is provided withteeth d. The ratchet wheel co-operates with a displacement pawl bintegral with a pawl carrier t pivoted at i and held in its normalposition by spring h. On the right side of pawl carrier t, a retainingpawl p is mounted on a pivot 1' and held in its normal or rest positionby spring s. The displacement pawl b has a wedge-like surface c which isprovided at the end thereof with a safety catch f. This safety catch ispreferably arranged at right angles to the direction of movement of theratchet wheel, as may be clearly seen from Fig. 1.

The left side of Fig. 1 shows a conventional key action comprising keylever K connected by link L to front link M which in turn is connectedby link N to the type lever T. Link S is connected at one end to memberO rigidly fastened to link N and at its other end is hooked around theuniversal bar u. The type lever T is held in its normal position bymeans of spring R and strikes on platen P when actuated. The lower endof the pawl carrier t is provided with a resiliently mounted littleroller a which is adjustable by means of screw o and is adapted toco-operate with the universal bar.

The operation of the aforesaid embodiment of my invention is apparent tothose skilled in the art. When key lever K is depressed, through link L,front link M and link N the type lever T will be actuated and willstrike against platen P. At the same time link S will pull the universalbar u, to the left which in turn will engage roller a and actuate pawlcarrier t. This will displace escapement pawl b so that its wedge shapedsurface c will rest on or will engage the ratchet tooth d as may be seenin Fig. 2. At the same time the detaining pawl p will release theratchet wheel and consequently tooth d under the influence of thecarriage spring will move in the direction of the arrow along and incontact with the wedge-like surface c of the displacement pawl b. Thisaction will cause the displacement pawl b to move out of its path untilthe ratchet tooth d with its surface e abuts the safety catch f asdepicted in Fig. 3. The pawl carrier t and the displacement pawl b underthe influence of spring it will continue their return movement as soonas the depressed key is released and they will return to their normalposition of rest. In this return movement, the pawl is assisted byhaving safety catch f sliding off surface g of the ratchet tooth.

Referring now to Figs. 5 to '7, they illustrate my improved wedge-likedisplacement pawl in co-operation with a ratchet wheel of conventionaldesign having rectangular teeth d-2. In view of the similarity ofconstruction, the description will not have to be repeated and similarreference characters are used to denote parts identical with thoseappearing in Figs. l to 4. The operation of this combination is similarto the one described hereinabove and will be readily understood from thedrawings showing the escapement in successive phases of its operation.The only difference is that due to the rectangular shape of pawl will bereturned to its normal position of rest immediately after the depressedkey has been released.

It is to be observed that the escapement operates in the describedmanner only when the key is allowed to return slowly to its normalposition of rest. When typing fast, the displacement pawl will bereturned completely to its normal position of rest in one movement dueto the rst impulse exercised by the ratchet tooth on the wedge surfaceof the displacement pawl.

In the other embodiment of my invention illustrated in Figs. 8 to 13, asafety catch is incorporated in each wedge-like tooth of the ratchetwheel which co-operates with pawls of conventional design. Similarreference characters are used in Figs. 8 to 13 to designate partsidentical with those described hereinabove and illustrated in Figs. l to7. Ratchet wheel lc-l is provided with wedge-like teeth d-l having asurface g-L At or near the end of each tooth, a catch -l is incorporatedwhich is preferably at right angles to the direction of rotation of theratchet wheel. Displacement pawl b-l and pawl carrier t-l which areintegral, are pivoted at i-l and the displacement pawl is capable ofengaging the teeth of the ratchet wheel and particularly safety catchf-l. The retaining pawl p l is pivotally arranged in the conventionalmanner on pawl carrier t-L Figs. 8 and 9 show the pawls in the normalposition of rest. When a key is depressed link s l will displace theuniversal bar u l to the left so that this will strike against screw v-Iand will actua-te the pawl carrier t-l. The end of the displacement pawlb-l will rest on or will be in contact with the wedge shaped surface g-lof tooth d-l as may be seen in Fig, 10. At the same time the retainingpawl p-l will release the ratchet wheel so that tooth d-l under theinfluence of the carriage spring communicated through the rack and geary will move in the direction of the arrow. This will move pawl b-l inthe direction of its normal or rest position until it engages or abutsthe the ratchet teeth :1 2 the displacement .f

safety catch f-l as may be seen in Fig. 11. In this manner, theescapement will be locked in this position momentarily and unintendeddisplacements of the carriage will be impossible before the key iscompletely released.

I have found that when manufacturing ratchet wheels embodying theprinciples of my invention, it is the simplest to make them from twopieces which are subsequently rigidly connected to each other. Animproved ratchet wheel made with this method may be seen in Figs. l2 and13. Part o of the ratchet wheel carries the wedge-like teeth and part nthe safety catches. After these parts have been made up separately andbrought in the correct position in relation to each other, they arerigidly united by means of screws, rivets or the like.

My improved escapement permits the insertion of a resilient memberbetween the universal bar and the pawl carrier of any typewriter. Ofcourse, the resilient member will have a suitable construction so as todisplace the pawl carrier from its position of rest when one of the keysis depressed. This construction produces an easy and elastic touch andhas a tendency to speed up the return movement of the type lever. Inaddition, the escapement operation proper will be much quicker andsmoother because the carriage spring will exercise greater force on thewedge surface than the associated resilient member or buffer spring.

Fig. 14 shows my improved ratchet wheel embodying a wedge-like surfaceand safety catch in co-operation with a conventional escapement similarto that of the well-known Royal typewriter. Fig. 14 closely resemblesthe escapement illustrated in Fig. 8, the displacement pawl 22-2 beingprovided with a small ball w rotatably mounted at the end of thedisplacement pawl. Similar reference characters have been used both inFig. 8 and Fig. 14 to denote identical parts. It is believed that theconstruction and operation of this particular embodiment of my inventionwill be readily understood by those skilled in the art from theforegoing description given in connection with Figs. 8 to 11.

Figs. 15 and 16 are fragmentary and diagrammatical views of twosuccessive phases in the operation of this escapement. Fig. 15 depictsthe position of the retaining pawl and of the displacement pawl inrelation to the tooth of the ratchet wheel when the key lever isactuated, while Fig. 16 shows the pawls in their locked position whenthe key lever has not been completely released yet.

I claim:

1. An escapement device for typewriters comprising a ratchet wheelhaving a plurality of teeth provided with bevel surfaces, a detainingpawl adapted to engage a tooth of said ratchet wheel in its normalposition of rest and to release same when actuated, a displacement pawlslidably receiving said disengaged tooth, means for actuating said pawlsduring the forward stroke of a type lever, and a short safety catchsurface for each tooth of the ratchet wheel adjoining the said bevelsurface substantially at right angles to the path of said tooth andadapted to co-operate with the sliding off displacement wall to retainand lock the ratchet wheel until the complete release of the depressedkey.

2. An escapement dveice for typewriters comprising a ratchet Wheelhaving a plurality of teeth bearing bevel surfaces, a detaining pawladapted tol engage a tooth of said ratchet wheel in its normal positionof rest and to release same when actuated, a displacement pawl capableof slidably receiving said disengaged tooth, means for actuating saidpawls during the forward stroke of a type lever, and a short safetycatch surface for each tooth of the ratchet wheel adjoining the saidbevel surface towards the displacement pawl substantially at rightangles to the path of said tooth, said safety catch surface beingadapted to engage the sliding off displacement pawl and to detain and tolock said ratchet wheel until the complete release of the depressed key.

3. An escapement device for typewriters having keys comprising a ratchetwheel having a plurality of teeth bearing angular surfaces, a pawlcarrier adapte-d toreceive impulses from the forward stroke on the keysof said typewriter, a detaining pawl mounted on said carrier andadap-ted to engage a tooth of said ratchet wheel in the normal positionof rest of the pawl carrier and to release same when said pawl carrieris actuated, a displacement pawl on said carrier adapted to slidablyreceive said -disengaged tooth, resilient means for maintaining saidcarrier and said pawls in their initial position, and a short safetycatch surface for each tooth of the ratchet wheel adjoining the saidangular surface towards the displacement pawl substantially at rightangles to the path of said tooth, said safety catch surface beingadapted to engage the sliding off displacement pawl and todetain and tolock said ratchet wheel until said carrier and said-key are completelyreleased.

4. In a ratchet wheel for typewriter escapements, the improvement whichcomprises a circular member having a plurality of teeth each bearing anangular surface, a second circular member Vhaving identical number ofteeth at right angles to the plane of said members and adapted to formextensions for said angular teeth, and means for rigidly connecting saidcircular members to each other.

5. An escapement device for typewriters cornprising a powered ratchetwheel having teeth, detaining and displacement pawls adapted to engageone of said teeth at a time and having surfaces co-operating withcorresponding surfaces on said ratchet wheel teeth, at least one of saidco-operating surfaces being at an angle other' than right angle to thedirection of movement of said ratchet wheel, means for actuating saidpawls during the forward stroke of a type lever to permit movement ofsaid ratchet wheel by one tooth, and a safety catch surface adjoiningsaid angle surface and at substantially right angles to the direction ofmovement of said ratchet wheel capable of locking the othercol-operating surface after the forward stroke of the type lever untilthe complete release of the depressed key. FRITZ EIBERT.

